Characterizations of Thermoplastic Block Elastomers Based on Polybutadiene and ϵ -Caprolactone

• Published in: Journal of macromolecular science. Part A, Pure and applied chemistry Pure and applied chemistry, 2010-06, Vol.47 (8), p.794-803
• Main Authors: Lemoine, Michael, Brachais, Claire-Helene, Boni, Gilles, Brachais, Laurent, Couvercelle, Jean-Pierre
• Format: Article
• Language: English
• Subjects: Applied sciences; complex viscosity; Exact sciences and technology; mechanical properties; Organic polymers; PB-PCL copolymers; Physicochemistry of polymers; Polymerization; Preparation, kinetics, thermodynamics, mechanism and catalysts; thermal properties
• ISSN: 1060-1325; 1520-5738
• DOI: 10.1080/10601325.2010.492041

A broad series of tri- and multiblock copolymers based on linear and branched oligomers of polybutadiene as central blocks and polycaprolactone (PCL) as block extremities are characterized by SEC, DSC, DMA, Dynamical Rheology and DRX. DSC analyses reveal phase separation between the two amorphous PB and PCL phases. By thermal analysis, the glass transition temperature of PCL is only detected for materials containing at least 80% w/w of PCL. This is attributed to the small length of the polyester blocks for copolymers containing less than 80% w/w of PCL. The increase of fusion heat with increasing PCL content in the copolymers is correlated to the greater ability of PCL chains to rearrange as HTPB amount decrease in the material. Regarding the evolution of the melting temperature of the various copolymers, the characterization by DMA and dynamical rheology confirms the behaviour observed by DSC. Mechanical and rheological properties (i.e., storage modulus and complex viscosities) were studied and reveal that the behavior of the copolymers depends on both the rate of PCL chains and on the nature of the elastomeric block.